1. Field of the Invention
The present invention relates to a projection device, particularly to a projection device of which the position of the optical engine can be adjusted so that focusing error can be improved and the quality of projected images can be enhanced.
2. Description of the Related Art
Referring to FIG. 1, a conventional projection device 90 has an optical engine 91, which is fixed to a base 92 and projects images to a reflection mirror or screen 93. The optical engine 91 is a high-precision instrument and has a specific design value of focal length. However, mechanical errors, assemblage errors, optical errors and transportation factors often cause the optical engine 91 moved along the Z-axis, that is the projection direction of the image. Consequent, the resulting focal length is deviated from the design value, which results in blurred images. Although an additional adjustment mechanism is available to adjust the focal length after the optical engine 91 is assembled, an adequate adjustment cannot be obtained because the optical engine 91 is fixed on the base 92. Therefore, the focal length of image projection along the Z-axis is still beyond the design value, which seriously affects the image quality. Therefore, how to design a projection device with the function of built-in focal-length adjustment mechanism, so as to ensure the image quality has become an important research subject in the field concerned.
In view of the problem that the conventional projection device lacks the adequate adjustment function of optical engine and in order to serve the society and advance the industry, a solution has been studied and sought. After years of studying, an adjustment mechanism for optical engine which has superior adjustability and operational convenience has been developed.